Fabrication and characterization of silica nanotubes with controlled dimensions

Silica nanotubes with controlled diameters and lengths were fabricated by a template-directed method. Nanowires composed of poly(2-dimethylaminoethyl methacrylate)-block-polystyrene (PDMAEMA–PS), which were fabricated by RAFT dispersion polymerization of styrene in methanol using PDMAEMA as a macro-RAFT agent, were used as sacrificial templates. The diameter of the polymeric nanowires can be adjusted by changing the degree of polymerization (DP) of the hydrophilic PDMAEMA block. As the chain length of the hydrophilic PDMAEMA block increases, the DP of the PS block for formation of the nanowires increases, leading to the diameter increase of the corresponding nanowires. Moreover, the polymeric nanowires with controlled lengths and diameters of the core and the shell can be fabricated on a large scale through polymerization-induced self-assembly and reorganization, conveniently. The weak polyelectrolyte, PDMAEMA shell, is an ideal nanoreactor for deposition of silica to form hybrid nanowires. Silica nanotubes were prepared by calcination of the hybrid nanowires.